This invention relates to the mounting of engines in vehicles and more particularly to the mounting of engines in skid-steer vehicles.
1. Field of the Invention
Skid-steer loaders are vehicles possessing a high degree of maneuverability and which are propelled and maneuvered by driving the wheels on one side of the vehicle at a different speed and/or in a different direction from those on the other side so as to achieve a turning motion. When the wheels on one side are driven forwardly and those on the opposite side rearwardly, the loader turns on its own vertical axis.
The drive mechanism of hydrostatic drive skid-steer loaders generally comprises an internal combustion engine having its output shaft coupled to a pair of axially aligned variable displacement pumps, the output of each pump directed to a respective one of a pair of motors which operate respective independent chain and sprocket drives on opposite sides of the vehicle. The hydrostatic drive mechanism for skid-steer loaders evolved from a mechanical clutch mechanism driven by the engine wherein a combination of belts and pulleys operatively connected to the chain and sprocket drive of the vehicle permitted the vehicle to operate in the skid-steer mode. Until the present invention, it has been difficult to adapt hydrostatic drive to the smallest of skid-steer vehicles. The present invention represents an improvement over prior hydrostatic drive mechanisms, which permits such adaptation.
2. Description of the Prior Art
A prior art vehicle with mechanical clutch drive is exemplified by U.S. Pat. No. 3,231,117 entitled "Tractor Vehicle and Drive Therefor" by C. E. Melroe et al which issued on Jan. 25, 1966. FIGS. 4, 5 and 6 of the Melroe et al patent disclose a clutch type mechanism wherein a shaft driven by the engine has mounted thereon an adustable sheave which is coupled by a V-belt to a split pulley connected to a jack shaft which is operatively connected through a pair of clutches to a drive chain which is drivingly coupled to primary drive sprockets which drive additional chains connected between the drive sprocket and the wheel sprockets, the wheel sprockets being coupled to respective stub axles of the vehicle. Independently operated clutches are provided on opposite sides of the vehicle and the clutches are manipulated to operate the vehicle in forward and reverse directions.
The current state of the art of a skid-steer loader with hydrostatic drive is exemplified by U.S. Pat. No. 4,055,262 entitled "Loader Main Frame for Skid Steer Loader" by James J. Bauer et al which issued on Aug. 25, 1977 to the assignee of the present invention and U.S. Pat. No. 4,168,757 entitled "Drive System for a Skid Steer Loader" by Joseph M. Mather et al which issued on Sept. 25, 1979 to the assignee of the present invention. FIG. 8 of U.S. Pat. No. 4,055,262 shows a hydrostatic drive wherein an engine 81 is coupled to a hydraulic pump mechanism 85 extending axially from the engine 81. Pump mechanism 85 comprises a pair of axially aligned variable displacement pumps which are connected respectively to motors 86 and 87 mounted on opposite sides of a transmission case for driving respectively independent chain and sprocket drives contained therein.
Vehicles of a similar size to those for which the present invention is primarily intended normally have employed clutch drive mechanisms similar to that of the U.S. Pat. No. 3,231,117. Design considerations have prohibited the incorporation of commonly used prior art hydrostatic drive mechanisms within the smaller vehicle body configurations. Accordingly, the present invention was devised to modify the prior art hydrostatic drives to achieve a new vehicle configuration of improved design. The features of novelty which characterize our invention are pointed out with particularity in the claims which form a part of this specification.